Relativistic momentum is 1% greater than classical, at what speed?

Click For Summary
SUMMARY

The discussion centers on calculating the speed at which relativistic momentum exceeds classical momentum by 1%. The relevant equations are P_r = mv/sqrt(1-(v^2/c^2)) for relativistic momentum and P_nr = mv for classical momentum. The user initially miscalculated the square root of 0.01970, leading to an incorrect speed of 0.0003884c instead of the correct value of 0.14c as stated in the textbook. The error was identified and corrected through peer feedback.

PREREQUISITES
  • Understanding of relativistic physics concepts
  • Familiarity with momentum equations
  • Basic algebra skills for manipulating equations
  • Knowledge of the speed of light constant (c)
NEXT STEPS
  • Review the derivation of relativistic momentum equations
  • Practice solving problems involving relativistic effects
  • Learn about the implications of relativistic speeds on mass and energy
  • Explore the differences between classical and relativistic physics
USEFUL FOR

Students studying physics, particularly those focusing on relativity, as well as educators looking for examples of common mistakes in momentum calculations.

chris_0101
Messages
59
Reaction score
0

Homework Statement


How fast must a body be traveling if its forrect relativistic momentum is 1% greater than the classical momentum


Homework Equations


P_r = mv/sqrt(1-(v^2/c^2))
P_nr = mv
p_r = 1.01P_nr

The Attempt at a Solution



mv/sqrt(1-(v^2/c^2)) = 1.01mv
mv = 1.01(mv)[sqrt(1-(v^2/c^2))]
1 = 1.01[sqrt(1-(v^2/c^2))]
1/1.01 = sqrt(1-(v^2/c^2))
(1/1.01)^2 = 1-(v^2/c^2)
0.980296 = 1-(v^2/c^2)
0.980296 - 1 = -(v^2/c^2)
-0.01970 = -(v^2/c^2)
(-0.01970)(c^2) = -v^2
0.01970c^2 = v^2
0.0003884c = v

However, this is not the correct answer. The actual answer in the back of the textbook is 0.14c. If anyone can correct my algebra or point me into the right direction it would be greatly appreciated.

Thanks
 
Physics news on Phys.org
chris_0101 said:
0.01970c^2 = v^2
0.0003884c = v

The square root of 0.01970 is not 0.0003884 :wink:
 
I cannot believe I overlooked that, it turned out I was squaring the 0.01970. Thanks a lot :)
 

Similar threads

Replies
9
Views
1K
  • · Replies 4 ·
Replies
4
Views
1K
Replies
7
Views
3K
  • · Replies 27 ·
Replies
27
Views
2K
Replies
5
Views
2K
Replies
14
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 7 ·
Replies
7
Views
943
  • · Replies 12 ·
Replies
12
Views
2K